Known as a conventional image pickup apparatus is an image pickup apparatus of Patent Document 1. FIG. 53 is an exploded perspective view of the image pickup apparatus of Patent Document 1. An image pickup apparatus 901 includes an iris member 902, an optical lens array 903, an optical filter 906, and an image pickup unit 907. In the image pickup apparatus 901, the iris member 902 having four openings 902-1, 902-2, 902-3, and 902-4 and the optical lens array 903 having four lenses 903-1, 903-2, 903-3, and 903-4 constitute four image pickup optical systems. Light beams which have passed through the image pickup optical systems, respectively, form images on four pixel groups 907-1, 907-2, 907-3, and 907-4, respectively, on the image pickup unit 907. The image pickup unit 907 constituted by a CCD sensor or the like is formed on a semiconductor substrate 910 together with a drive circuit 908 and a signal processing circuit 909.
The signal processing circuit 909 sequentially reads out pixel information of the image pickup unit 907 by the drive circuit 908, receives the pixel information as pixel signals, calculates values of parallaxes of respective pixel groups (907-1, 907-2, 907-3, and 907-4) from the pixel signals, and calculates distances based on the parallaxes.
Patent Document 1: Japanese Laid-Open Patent Application Publication No. 2003-143459